The function of the Imaging Core is to test novel imaging approaches and image analysis algorithms, streamline these techniques for in vivo imaging of cortical plasticity, and supply the optimized protocols and software to the investigators in the Center. The approaches optimized by the Imaging Core will be used in Projects 1, 2 and 3 of the Center for multidisciplinary, comprehensive studies of the role of specific genes in anatomical cortical plasticity. The Core is a cost effective and efficient way of providing imaging and analysis techniques to investigators in the Center. Specifically, the Core will: 1. Screen novel transgenic mice for markers for in vivo imaging that label specific aspects of neural anatomy, such as specific inhibitory interneurons and laminar-specific pyramidal neurons. 2. Catalog which labeled lines are bright enough for in vivo imaging and how this brightness changes with development. 3. Catalog which labeled lines express in visual, barrel, and anterior cingulate cortices 4. Screen newly-advanced genetically-encoded markers of neuronal function (e.g. calcium indicators and voltage sensors) to determine which are suitable for in vivo imaging. 5. Develop novel image analysis tools to automate the quantification of axonal and dendritic structural plasticity (e.g. changes in branching, branch length, spine volume, spine and bouton density, spine kinetics). 6. Continually fine-tune the surgical preparation for live imaging of cortical neurons. By assigning these tasks to one facility, the Center gains an economy of scale in which the time devoted to working through these important issues is absorbed once by the Core. Thus, each lab in the Center is not individually burdened with the costs in time, people, and resources necessary to work through and optimize the imaging approaches necessary to accomplish the projects proposed by the Center. Additionally, the Core will insure that the imaging approach used by each laboratory is uniformly agreed upon by each of the members of the Center and is of the highest possible quality.